Mechanical breathing apparatus



March 3, .1959 E. A. J. 'ruNNlcLlFFl-z ETAL 2,875,946

. MECHANICAL BREATHING APPARATUS Filed sept. 13, 1956 4 Sheets-Sheet 1 WIM-wann' IIIIHHIIIIHIIHIIIIHllilllllpllllllv Il March 3, 1959 E. A. J. TUNNICLIFFE. ETAL 2,875,946

MECHANICAL BREATHING APPARATUS Filed Sept. 13, 1956 4 Sheets-Sheet 2 Inventors.'

Balm rwaqm Attorneys March 3, 1959 E. A. J.TUNN1cL|FFE ET AL 2,875,946

MECHANICAL BREATHING APPARATUS 4 ksheets-sheet :s

Filed Sept. 13, 1956 March 3, 1959 AE. A. J. TUNNxcLu-FE ET AL MECHANICAL BREATHING APPARATUS Filed Sept. 13, 1956 4 Sheets-Sheet 4 I E! d' IU Tlnventos:

Y *Balm www Attorney United States Patent 2,875,946 MECHANICAL BREATHING-APPARATUS Edward Albert James Tunnclite, Kensington, London, and Coston Lane Densham, Brighton, England, assignorsto Electronic and X-Ray'Applications Limited and Wade Engineering Limited f Application September 13, 1956, Serial{No. 609,763

Claims priority, application Great Britain September 13, 1955ir 5 Claims. (Cl. 230-42) This invention is concerned with-.mechanical breathing apparatus for use in maintainingthe breathingaction of a human being by the application *ofV a pulsating Vpressure to some part at least of the thoracic area and/or"ab dominal area.

Itis now usual to set up the pulsatingpressure by the application of a pulsating air pressure to the apparauts: in the use of such apparatus, it is essential that the pulsating air pressure shall be capable of, wide regulation to suit the= different cases and conidtions whicharise: this invention is more particularly concerned with mechanism to establish the pulsatingk pressure air supply and itl has for its object to proivde a mechanism which shall be capable of a wide rangev of adjustment tov enable the different requirements to be met.

In carrying out this invention the mechanism comprises a positive displacementair pump, a dischargeV duct for connectionrto a mechanical breathing apparatusvalve means to open and close the discharge duetto the intake and output side of the pump, a variable speed drive to operate the valve means in constantly recurringcycles and adjustable pressure-control valves controlling the connection of the intake and output sides ofA the pump to atmosphere.

In view of the use for which such mechanism is intended, it is desirable that the pump shall be of` a. type which does not require lubrication of` itsair contacting surfaces. For this reason the pumpy employed is preferably. of therotating lobe type in which the lobes are driven in synchronism with a constantsmall clearance .between,v their cooperating air displacement surfaces: such a type is exempliiied by the well known Rootes Blower type;

The valves which control the connection of the discharge duct respectively to the intake and output sides ofthe pump (these valves being referred to as the phasing valves) control the setting up of the impulses in each cycle as they alternately connect the duct to the low pressure (suction) side of the pump and the high pressure (delivery) side: the timing ofoperation of the two valves determines the relative timing of the high and low pressure phases in each cycle andthe perodicity-of the cycles will depend on the-speedatwhich the, valves are-operated: the maximum and minimum pressure values in the high and low pressure phases will depend on the' settingof the adjustable pressure-control valves. Such a machanism therefore enables variation to be madeV within a very wide range and so enables the breathing apparatus which is associated with the mechanism to dealy adequately with the various requirements- When'the pump output'is diverted from the discharge duct, it can pass direct to atmosphere or it can be taken to the intake side of the pump so as to enable the heat of compression of the air to be utilized in raising the temperature of the air passing to the intake side.

The operating mechanism for the phasing valves can be formed by a rotatable cam which is driven continuously at a variable rate: the form of the cam when taken in 2- conjunction with the' shapingr of the. control ports; of.'r the valvesthemselves will'enablef` the rate, ofv change of` the two phases to be chosen tomeet. the. conditions. imposed in the use of ther mechanism.

The-invention is illustratedby, way, of` example in the accompanying drawings;in.which.Figure. 1. isa sectional side elevation of a unit comprising the. pump, the various valves and a variable` speedy driving mechanism,. Figure 2 is an end elevation ofthe unit. Figure' is a sectionalrview showingthel arrangement. of*y certain tlow passages, Figure 4 is aperspective viewy of. theV phasing valve, andFigures 5., 6'. and 7 are diagrammatic, views showingl the phasingvalve in three, different` positions.

Referring to the drawings, 1v indicatesthe casingofa Rootes blower having an intake or suction. duct 2. and a pressure duct 3: such a formofpump is wellknown. and further description of itis believedto be unnecessary,- it being sufficient to say that` the blower comprisestwo lobedvrotors which are driven insynchronisrn andvwhich serveto draw-in air through the ductA 2` (which .therefore is at negative pressure) and deliver the air. to thev duct 3 (which. is therefore, at a positive pressure) The ducts 2 and Spass up about the opposite-sides of the pump casing 1 to a valve housing 4: from this housing extend ducts 5, 6 which are open, attheinendstothe atmosphere, the duct 5y aligningwiththe-suction duct 2 and the duct 6 aligning with theprressuretduct4 3. From this housing 4 `also extends a dischargeduct 7. Which-is arranged toreceive one end of a llexible-pi'pe,8:theI other end of which is arrangedto be connected to themechanh cal breathing apparatus which canbe o tanyknownkind.

The various ducts`,2.3,y 5., 6 andf7y opentothe cylinf drical bore of the housingvand within this bore isa phasing valve cock or plug 9. This valve, is cut. away as is shown'in Figure 4 toprovide twov transfer recesses 10, 11 whichfare spacedapart lengthwise; of` the plugf. The cross sectional form of they transfer: recessesisy iden tical but the recesses are angularly. displacedfrom. one another about the axis of theplug, therecessesdeaving blanking lands 12, 13 which are also angularly displaced; The land -12 controls the connectiorntoV thepressureduct 3 while the land 13 controls the connectionto vthesuction duct 2. y

The plug9 is oscillated sol asi to connectvtherduct 7. alternately to the-suction-duet2 and the pressure duct` so as to set up the required pulsating air. pressure in the vduct 7. Moreover, the arrangement is such that. the

pump is always in operation andin thepressure phase of the pulsatingairl pressuredraws air.V inffrorn thefatmoszphere and delivers the airto ther duct'7fandintheV negative pressure'phase draws air from thel duct-7 an'ddischarges that air to atmosphere.

The operation will'be more, clearly understood from Figures 5-7: in Figure 5, the landsy 12 and 13= both shut the duct 7 so that the duct isr isolated fromV the suction and pres-sure ducts Z, 3, therecess 11 connecting the suction duct 2 with the open ductl 5- to enablev f the pump to draw-in air 'and the-recess lthconnectingl the pressure duct 3 with the open duct so that'the air is discharged to atmosphere; The position shown` in Figure 5 is `an intermediate position whichlthe plugpasses through in moving fromoneextremeposition'toanother;

'ln Figure 6 is Ishown the position occupied-byther-plug after' it has passed through the= intermediate position ofv Figure 5 to the position to set up a positive pressure in the duct 7: in this position the suction duct 2 is connected by the recess 11 to the open duct 5 yand the corresponding land 13 isolates the duct 7 from that connection: in addition, the recess 10 connects the pressure duct 3 with the duct 7 and the corresponding land 12 closes the duct 6. Thus the pum-p draws in air from and` the atmosphere and delivers that air under pressure to the duct 7.

In Figure 7 is shown the position occupied by the plug after it has passed from the position of Figure 6 through the intermediate position of Figure to the position to set up a negative pressure in the duct 7: in this positon'the suction duct 2 is connected to the duct 7 via. the recess 11, and this connection is isolated from the open duct 5 by the corresponding land 13: the recess connects the pressure duct 3 to the open duct 6 and the corresponding land 12 closes the duct 7 from that connection. Thus the pump draws air from the duct 7 and discharges that air to atmosphere.

It will be clear that the land 12 and the associated recess 10 constitute one phasing valve which controls the pressure duct 3 and the land 13 and associated recess 11 constitute another phasing valve controlling the suction duct 2: the valves could therefore be formed as separate entities but it is preferred as shown to in.

corporate them in the one plug.

The plug 9 is arranged to be oscillated from one extreme position to the other by a cam 14 which is detachably clamped on a spindle 15 by a nut 15', the cock 9 being supported for angular movement on that spindle: the cam is engaged by a follower 16 on a bracket 17 carried -by a slide 17 which is urged upwardly by a spring 18, the bracket having guide rollers 19 cooperating with a fixed guide rod 20 which holds the bracket 17 from turning. The bracket is formed at its upper end with a jaw head 21 which cooperates with an anti-friction bearing on a stud 22 carried by va crank arm 22 at the end of the plug 9.

The spindle 15 which carries the cam 14 is driven by an electric motor 23 which also drives the Rootes blower, the drive from the motor to the spindle 15 being effected through a pulley-cumbelt drive 24, a variable speed device 25 of the conical pulley type, and through a reduction gear train 25A.

As the spindle 15 is turned, the cam 14 causes the tube or slide 17 to rise and fall and this in its turn causes the crank arm 22' and hence the plug 9 to oscillate in the casing 4 between the positions shown in Figures 6 and 7 through the position shown in Figure 5, so etecting the change-over operation described.

Thus in the arrangement according to the invention, the form of the plug 9 and the form of the cam 14 determines the relative timing of the high and low pressure phases occurring in the duct 7, and both factors, and particularly the form of the cam, determine the rate of change between the two phases: the detachability of the cam 14 enables this timing and rate to be chosen to suit any desired pattern of mechanical Abreathing action by the fitting of an appropriately shaped cam. The periodicity of the cycles each having a low and a high pressure phase will depend on the speed at which the cam 14 is rotated and this can be selected by regulation of the variable speed device 25. In order to provide also for regulation of the maximum and minimum pressures in the high and low pressure phases, the suction and pressure ducts 2 and 3 are extended at 2', in effective shunt across the valve 9 to open ends having two-way communication with the atmosphere and in which control valves 26, 27 are respectively fitted, these valves being Iarranged for independent operation.

It is preferred, as is shown, to limit the maximum pressure change which can occur on the intake and output sides of the pump: for this purpose, the ducts 2 and 3 can be equipped with automatic valves 28, 29 the valve 28 opening inwardly if the suction in the duct 1 increases beyond a predetermined figure, and the valvr 29 opening outwardly if the pressure in the duct 3 rise` beyond a predetermined value.

Instead of discharging the output of the pump to at mosphere via the duct 6, provision can be made to con neet the duct to the input side of the pump so that the heat content of the air due to its compression can bt transfererd to the air passing to the pump intake.

The unit shown in Figures 1 and 2 can form a mounting for an instrument and control panel, the panel pro viding a mounting for the controls for the apparatus and instruments to indicate the values of the variables regulated by the controls.

Apparatus according to this invention enables the various conditions which arise in the use of mechanical breathing apparatus to be met in a simple fashion and by the usc of parts which are little liable to derangement.

The action of the mechanism is that of enabling the Ilow of air set up by a pump to be variably drawn upon to produce the mechanical breathing action to suit any particular case.

We claim:

1. Mechanism for setting up a pulsating air supply to a mechanical breathing apparatus, said mechanism comprising a constantly running positive displacement air pump having a suction duct and a pressure duct; a discharge duct for connection to the breathing apparatus; phasing valve means for connecting said discharge duct alternately to said suction duct and said pressure duct; means for operating said phasing valve means in constantly recurring cycles; and other valve means for controlling two-way communication between the atmosphere and both said suction duct and said pressure duct independently of said phasing valve means.

2. Mechanism as set forth in claim l including means for varying the speed of said phasing valve operating means, and pressure operated means for regulating the pressures in said suction duct and said pressure duct respectively.

3. Mechanism as set forth in claim 1 in which said phasing valve means comprises a valve plug having a part operable for connecting said suction duct alternately to the atmosphere and to said discharge duct, and a part `operable for connecting said pressure duct alternately to said discharge duct and to the atmosphere.

4. Mechanism as set forth in claim l in which said phasing valve means comprises a valve housing having a connection to said suction duct, a connection to said pressure duct, a connection to said discharge duct and a connection to the atmosphere, and an oscillatable valve plug in said housing; and variable speed means for oscillating said valve plug to control communication between said connections.

5. Mechanism as set forth in claim l in which the phasing valve operating means comprises cam mechanism including an interchangeable cam, and variable speed means for operating said cam.

References Cited n the tile of this patent UNITED STATES PATENTS 

